1. Field of the Invention
The present invention relates generally to a method of controlling gated transmission (i.e., intermittent transmission of a dedicated control channel signal) between a base station (UMTS Terrestrial Radio Access Network, UTRAN) and a mobile station (User Equipment Mobile Station, UE(MS)) in a W-CDMA (Wideband-Code Division Multiple Access) communication system, and in particular, to a method of efficiently using dedicated channels for transmission of packet data.
2. Description of the Related Art
A conventional CDMA communication system, principally configured for transmission of voice and data, transmits data on a dedicated channel. To do so, a dedicated channel is assigned to transmit data and is released after the data transmission is complete. The assignment and release of resources is frequently done to provide services other than voice service, such as packet data service in the conventional method. The resulting reconnection time delay makes it difficult to provide satisfactory voice services. In many cases, packet data is discontinuously transmitted, wherein a non-transmission period is interposed between packet transmission periods. When transmitting packet data discontinuously using the conventional channel controlling method, the channel should be either released or maintained during the pauses between data transmission. If the channel is released, reassignment of the channel is time consuming and thus a satisfactory packet data service cannot be provided. On the other hand, channel maintenance ties up resources and increases power consumption causing interference.
Accordingly, there is a need for developing a new method of assigning a channel to provide services other than voice service, for example, packet data services. FIG. 1 illustrates the various states of an UE(MS) defined according to the type of radio resources assigned for data transmission in a W-CDMA communication system.
Referring to FIG. 1, the various channel states of the UE(MS) are categorized into a Cell_DCH state where a dedicated channel is assigned for data transmission, a Cell_FACH state which allows only transmission of a small amount of data on a common channel, a Cell_PCH state which requests an UE(MS) position to be registered in terms of a cell, and a URA_PCH (UTRAN Registration Area_PCH) state which requests an UE(MS) position to be registered in terms of a UTRAN Registration Area (URA). No data transmission is allowed in both the Cell_PCH and URA_PCH states. Assignment of a dedicated channel to an UE(MS) in the Cell_DCH state is considered in two ways: first, the dedicated channel is continuously used until it is released; and second, the dedicated channel is used only while a predetermined amount of data is transmitted or data is transmitted for a predetermined time. The conventional method supports an intermittent burst data transmission service by allowing continuous use of a dedicated channel until all the data is transmitted, or releasing a dedicated channel after transmission of burst data and then reassigning the dedicated channel by use of a dedicated reassignment request message on a common channel. In the former case, uplink and downlink dedicated control channels should be transmitted continuously to maintain them even in the absence of data to be transmitted on a dedicated data channel, thereby dissipating the channels and unnecessary power. In the latter case, services cannot be provided stably because the time to reassign channels varies.
FIGS. 2A to 3B are the structures of signals transmitted from a UTRAN and an UE(MS) according to the conventional technology.
FIG. 2A illustrates the structure of an UE(MS) transmission signal upon the absence of data to be transmitted on a uplink DPDCH (Dedicated Physical Data Channel) during uplink data transmission, and FIG. 2B illustrates the structure of a UTRAN transmission signal upon the absence of data to be transmitted on a downlink DPDCH during downlink data transmission. Reference numeral 200 in FIG. 2A and reference numeral 250 in FIG. 2B denote time points when transmission of dedicated data channels are stopped due to absence of transmission data on the uplink DPDCH and on the downlink DPDCH, respectively. After the time points, only dedicated physical control channels(DPCCH) are continuously transmitted so as not to lose synchronization of the uplink and downlink. The continuous transmission of the dedicated control channels (DPCCHs) is advantageous in that when uplink or downlink transmission data is generated, the data can be reliably transmitted on the dedicated data channels (DPDCHs) without any time delay. This can be confirmed from FIGS. 3A and 3B.
FIG. 3A is a signal diagram illustrating data transmission on a uplink dedicated data channel (DPDCH) upon generation of data to be transmitted on a uplink during transmission of only a uplink dedicated control channel (DPCCH), and FIG. 3B is a signal diagram illustrating data transmission on a downlink dedicated data channel (DPDCH) upon generation of data to be transmitted on a downlink during transmission of only a downlink dedicated control channel (DPCCH). Reference numeral 300 in FIG. 3A and reference numeral 350 in FIG. 3B denote time points when data transmission resumes on the dedicated data channel. Frames are transmitted again immediately after the time points when transmission data is generated. Unfortunately, the continuous transmission of uplink and downlink dedicated control channels (DPCCHs) increases interference on the uplink and downlink. As a result, uplink and downlink channel capacities are decreased and UE(MS) power consumption is increased.
Therefore, gated transmission of dedicated control channels (DPCCHs) is preferable in order to use the transmission channels efficiently and to provide stable service. Gated transmission also minimizes the increase of interference caused by the continuous transmission of bidirectional dedicated controls channels and the increase of power consumption in an UE(MS).
It is, therefore, a first object of the present invention to provide a method of gated transmitting a dedicated control channel (DPCCH) in a gated mode when data is not transmitted on a dedicated data channel for a predetermined time after the dedicated channel is assigned in a mobile communication system.
It is a second object of the present invention to provide a method of gated transmitting a uplink dedicated control channel signal in a gated mode by requesting a gated transmission to a UTRAN when an UE(MS) has no data to be transmitted on a uplink for a predetermined time in a mobile communication system.
It is a third object of the present invention to provide a method of gated transmitting a downlink dedicated control channel signal in a gated mode by controlling an UE(MS) when there is no data to be transmitted on a downlink for a predetermined time in a mobile communication system.
It is a fourth object of the present invention to provide a method of gated receiving a uplink dedicated control channel signal in a gated mode from an UE(MS) by a UTRAN in a mobile communication system.
It is a fifth object of the present invention to provide a method of gated receiving a downlink dedicated control channel signal in a gated mode from a UTRAN by an UE(MS) in a mobile communication system.
It is a sixth object of the present invention to provide a method of transmitting data on a uplink by an UE(MS) when transmission data is generated during gated transmission in a mobile communication system.
It is a seventh object of the present invention to provide a method of transmitting data on a downlink by a UTRAN when transmission data is generated during gated transmission in a mobile communication system.
Briefly, these and other objects can be achieved by providing a gated transmission method. In the gated transmission method, a first party transmits a message indicating that a gated transmission condition is satisfied. Upon receipt of a response message from a second party, the first party transmits a gated transmission command message. Then, the first party performs gated transmission according to parameters included in the gated transmission message. The parameters include a gating rate, a gated transmission start time, a gated transmission pattern, and a power increment by which to increase the transmission power of a channel when transmitting data on the channel during the gated transmission.